Magnet unit



H. SACHS MAGNET UNIT Aug. 9, 1932.

Filed May 11, 1931 vI/II/IIIII INVENTOH M Patented Aug. 9, 1932 PATENT,OFFICE HUGO SACHS, OF LEIPZIG, GEBMANY MAGNET UNIT Application filed May11,1931, semi No. 536,583, and in Germany May 15, 19:0.

The invention relates to a magnet unit with armature adapted to vibratein both directions between oppositely disposed poles and adjustablerelatively thereto, for use in lolpd speakers, gramophone pickups andthe Units of this kind are already known, in which the poles of themagnet are adapted to be displaced in the direction of vibration of thearmature and are influenced by springs.

Such adjustability of the poles in the direction of vibration of thearmature has the following disadvantages. If the poles are springinfluenced, they themselves tend to vibrate, and the armature thussustains losses of energy. If the springs are not of exactly equalstrength, the one pole shoe may move further away from the armature thanthe H other, so that, eventually, the armature may still be adhering tothe one pole shoe while already out of contact from the other. The sameresult also occurs when the armature is not accurately centered betweenthe poles, to effect which exactitude is essential in the known units.

According to the invention, these drawbacks are obviated by forming thearmature wedge-shaped between the poles, the poles or pole-shoesthemselves being also of corre sponding form, so that, by sliding orturning the poles, which are perfectly rigid in the direction ofvibration of the armature, or bymoving the entire frame of the magnet,transversely relatively to the direction of vibration of the armature,the distance between the armature and the pole-shoes can be diminishedor increased at will, without causing the spacing between the pole-shoesand the armature to be unequal.

Thus in the electromagnetic unit of the present invention, the armatureadapted to oscillate in both directions is arranged be tween oppositelydisposed pole-shoes which are rigidly mounted in relation to each otherbut are adjustable as a whole in relation to the armature.

In addition to the improved and more accurate adjustment obtained inaccordance with the invention, the assembling of the 50 unit isconsiderably simplified.

Various embodiments of units in accord ance with the invention arediagrammatically illustrated in the accompanying drawing, in which Fig.1 is a side elevation of one embodip5 ment, and

Fig. 2 is a transverse section through Fig. 1. i

Fig. 3 is a sectional front elevation of a modification, and

Fig. 4 a side elevation thereof.

Fig. 5 is a perspective View of a further modification; and

Fig. 6 is a perspective view of the assembled unit according to Fig. 5.

In the drawing, like parts are denoted by like reference characters.

In the embodiment illustrated in Figs. 1 and 2, a, a denote two magnetswhich are rigidly connected with pole-shoes b and c by means of screws6, 0 respectively. The magnets a and a are movably secured to a frame 6by means of screws and nuts 8, s mounted in slots 7' of the frame 6. Gdenotes a bracket connected to the magnets a, a to .which bracket isanchored the head f of a screw spindle f. The spindle f passes through acorrespondingly screw-threaded hole 6 in the frame 6. The free ends ofthe pole-shoes b and 0 are wedge-shaped and mounted therebetween is awedge-shaped armature cl which is secured to the frame 6 by means of alugor bracket d fast with the frame e. 'The armature d is connected bymeans of rods 0 p g to the diaphragm of a loud speaker (not shown). 70denotes the energizing coils for the armature 05.

The poleshoes Z), c are. provided with holes or slots which are largerin the vertical direction than the diameter of the shanks of theretaining screws 6, 0 so as to enable each pole to be separatelyinitially adjusted so as to make contact with the armature (Z when theretaining screws .7), c are eased.

The operation is as follows The magnets a, a and pole-shoes b, 0 areinitially so adjusted that the pole-shoes b and a contact completelywith the Wedgeshaped armature d which is fixed in relation to the frame6. The retaining screws b", a v

are thereupon tightened and the screw spindle f is turned until thedesired air gaps are obtained between the surfaces of the armature d andof the pole-shoes b and c.

The screw bolts 8 are thereupon tightened and the unit is ready for use.

Since the pole-shoes b, 0 are rigidly con nected with the magnets a, awhich in turn are rigidly interconnected, the whole forms the unit whichcan be displaced horizontally in relation to the armatured, leaving theair gaps between the armature (Z and the poleshoes I; and 0 respectivelyalways equal.

Figs. 3 and a illustrate an embodiment in which a single magnet a andits rigidly attached pole-shoes b, 0 are adapted to be swungabout thetwo pivots h, h in the frame 0, whilst the wedge-shaped armature (Z issecured on the frame 6 as in the embodiment shown in Figs, 1 and 2, Inthis embodiment, the air gap between the armature d and poleshoes Z) and0 is increased by turning the magnet in one direction relatively to thestationary armature and decreased by turn ing the same in the oppositedirection.

A further embodiment is shown in Figs. 5 and 6 in which the entiremagnet a, including its rigidly attached pole-shoes Z), c, is adapted toswing about the pivots z, i. The ends of the armature d in thisconstruction, are

wedge-shaped in opposite directions between the respective poles, thefaces of which are correspondingly shaped.

As will be obvious from the drawing and description, the adjustment ofthe poles is always transverse relatively to the direction of vibrationof the armature, and owing to the rigid mounting of the poles orpole-shoes thereby permitted, losses which would otherf wise occurthrough vibration of these mem-V bers themselves are precluded.Moreover, springs and the like are entirely dispensed with, and thewedge-shape of the armature enables very accurate adjustment to beeffected,

I claim I 1. An electromagnetic unit for use in loud speakers,gramophone pickups and the like, comprising a frame, a magnet, polepieces with oblique ends rigidly attached to the poles of said magnetwith their oblique ends facing each other and converging, avibratory-armature of a shape corresponding to the gap between theoblique ends of said pole pieces, located between said oblique ends andresiliently supported on said frame, energizing coils co-operating withsaid armature, and means for moving said pole pieces as a unittransversely to said armature to ensure equal adjustment of the :airgaps between comprising a frame, amagnet, pole-pieces with oblique endsrigidly attached to the poles of said magnet with their oblique endsfacing each other to leave a wedge-shaped air gap, a vibratorywedge-shaped armature,

located between said oblique ends and resiliently supported on saic.frame, energizing coils cooperating with said armature, and means formoving said pole pieces as a unit transversely to said armature toensure equal adjustment of the air gaps between each face of thearmature and the corresponding oblique face of the pole piece.

3. An electromagnetic unit for use in loud speakers, gramophone pickupsand the like, comprising a frame, a magnet, pole pieces with obliqueends rigidly attached to the poles of said magnet with their obliqueends facing each otherto leave a wedgeshaped air gap, a vibratorywedge-shaped armature, located between said oblique ends and resiliently supported on said frame, energizing coils cooperating with saidarmature, and a screw spindle for moving saidmagnet and the pole piecesas a unit transversely to said armature to ensure equal adjustment ofthe air gaps between each face of the armature and the correspondingoblique face of the pole piece.

4:. I Anelectromagnetic unit for use in loud speakers, gramophonepickups and the like, comprising a frame, a magnet, pole pieces withoblique ends rigidly attached to the poles of said magnetwith theiroblique ends facing each other to leave wedge=shaped air gap, avibratory wedge-shaped armature located between said. oblique endsandresiliently supported on said frame, energizing coils co-operating withsaid armature and pivots pivoting said magnet and pole pieces as a unittransversely to said armature to 7 ensure equal adjustment of the airgaps between each face of the armature and the corresponding obliqueface of the pole piece.

5. An electromagnetic unitfor use in -loud speakers, gramophone pickupsand the like, comprising a frame, 7 a magnet, pole pieces with two pairsof oblique ends attached to the poles ofsaid magnet with each pair ofoblique ends facing each other to leave wedge shaped air gaps, avibratory armature with its ends wedge-shaped located between saidoblique ends and resiliently supported on said frame, energizing coilsco-operating with said armature, and pivots pivoting said magnet andpole pieces as a unit transversely to said armature to ensure equaladjustment of the air gaps between each face of the armature and thecorrespending oblique face of the; pole piece. I

In testimony whereof, I ailix my signature.

' nueo SACHS,

